Project Summary/Abstract Glioblastoma (GBM) is the most common primary brain tumor, and one of the deadliest forms of cancer. Standard surgery, chemotherapy, and radiation fail to eliminate the infiltrative, invasive cancer cells. Median survival remains only ~15 months. Drugs that seek out the disseminated GBM cells behind the blood-brain barrier will prevent the inevitable recurrence in patients. Based on their unique tumor-tropic migration and long- term drug delivery, engineered neural stem cells (NSCs) have shown enormous promise as a new approach to GBM therapy. However, procurement of appropriate cells for NSC- based therapy has been a significant challenge. The ideal NSC would be easily isolated and autologous to avoid immune rejection. To overcome the challenges with isolating autologous NSC from the brain, we discovered that transdifferentiation (TD) creates tumor-homing drug carriers capable of regressing GBM. Using a defined set of transcription factors, we switched the fate of mouse and human skin fibroblasts in induced NSCs (iNSCs) that homed to GBM with the same directionality as brain-derived NSCs. iNSCs genetically engineered to release the cytotoxic gene products dramatically reduced human GBM xenografts in mice and markedly extended median survival. Falcon Therapeutics now proposes to take the critical translational step. The objective of this proposal is to investigate this novel approach to cancer therapy using iNSC-based carriers from GBM cancer patient fibroblasts (iNSCPD). We will explore the following specific aims: 1) Determine if engineered iNSCPD are safe drug carriers that migrate to recurrent human GBM foci; 2) Determine if intracavity iNSCPD therapy is an effective treatment for post-surgical patient-derived GBM. This will be accomplished using a new TD approach we discovered that generates iNSCPD fast enough for clinical GBM therapy. We will use iNSCPD variants we developed that express optical reporters and/or prodrug/enzyme therapies that mimic clinical NSC therapy for GBM. We will employ our unique models of GBM resection/recurrence in mice and transplant iNSCPD on our newly identified clinically- compatible matrices to maximize the clinical relevancy of our findings. Once complete, our studies promise to identify a new approach to autologous NSC therapy that is easily translatable to human patient testing. This will address a critical gap in current NSC-based treatments for GBM, serve as a springboard for the field of iNSC-based carriers to improve cancer treatment, and begin to move this promising therapy towards clinical trials as well as commercialization.